Why performance of Vulkan is so poor ?

[r3d9u11]

Hello. I'm facing the trouble I have a poor FPS with Unreal Engine 4 when in uses Vulkan target.

So with same hardware stuff and same scene I have:
Windows 10 = 100 FPS (+/- 5)
Ubuntu 18.04 (KDE Neon) with OpenGL4 target = 85-90 FPS
Ubuntu 18.04 (KDE Neon) with Vulkan taget = 25-35 FPS

The main question: why is so big difference beetween OpenGL 4 and Vulkan ?

Here is my environment:

  PROCESSOR:          Intel Core i7-8550U @ 4.00GHz
    Core Count:       4                                        
    Thread Count:     8                                        
    Extensions:       SSE 4.2 + AVX2 + AVX + RDRAND + FSGSBASE
    Cache Size:       8192 KB                                  
    Microcode:        0xb4                                     
    Scaling Driver:   intel_pstate powersave                   

  GRAPHICS:           NVIDIA GeForce 930MX 2GB
    Frequency:        954/1001MHz      
    OpenGL:           4.6.0            
    Vulkan:           1.1.102          
    Display Driver:   NVIDIA 430.50    
    Screen:           1920x1080        

  MOTHERBOARD:        HP 837D
    BIOS Version:     Q85 Ver. 01.02.05                             
    Chipset:          Intel Xeon E3-1200 v6/7th                     
    Audio:            Conexant CX8200                               
    Network:          Realtek RTL8111/8168/8411 + Intel 8265 / 8275

  MEMORY:             8192MB

  DISK:               1000GB HGST HTS541010B7
    File-System:      ext4             
    Mount Options:    relatime rw      
    Disk Scheduler:   MQ-DEADLINE      

  OPERATING SYSTEM:   neon 18.04
    Kernel:           5.0.0-31-generic (x86_64)                                                                                   
    Desktop:          KDE Plasma 5.17.0                                                                                           
    Display Server:   X Server 1.19.6                                                                                             
    Compiler:         GCC 7.4.0 + Clang 6.0.0-1ubuntu2                                                                            
    Security:         l1tf: Mitigation of PTE Inversion; VMX: conditional cache flushes SMT vulnerable                            
                      + mds: Mitigation of Clear buffers; SMT vulnerable                                                          
                      + meltdown: Mitigation of PTI                                                                               
                      + spec_store_bypass: Mitigation of SSB disabled via prctl and seccomp                                       
                      + spectre_v1: Mitigation of usercopy/swapgs barriers and __user pointer sanitization                        
                      + spectre_v2: Mitigation of Full generic retpoline IBPB: conditional IBRS_FW STIBP: conditional RSB filling

Nvidia:
$ nvidia-smi

Thu Oct 17 13:50:38 2019       
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 430.50       Driver Version: 430.50       CUDA Version: 10.1     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|===============================+======================+======================|
|   0  GeForce 930MX       Off  | 00000000:01:00.0 Off |                  N/A |
| N/A   47C    P0    N/A /  N/A |    506MiB /  2004MiB |     14%      Default |
+-------------------------------+----------------------+----------------------+

OpengGL and Vulkan info:

OpenGL version string: 4.6.0 NVIDIA 430.50
Vulkan Instance Version: 1.1.114

I want be sure that it is not fail exactly of UnrealEngine4.
I should know whose that issue: Nvidia, Khronos or Epic ?

So I should to make detailed benchmark for OpenGL4 and Vulkan with my staff, how I can do it correctly?
Any ideas? (Or maybe somebody know what I'm doing wrong? Why Vulkan have a so poor perfomance?).

Please, help.
Thanks!